Chapter 22

1. Chapter 22 Planet in Crisis

2. Pollution • world is one highly interactive biosphere • damage to one ecosystem can have ill effects on many others • widespread effects = global change • one of most serious problems facing humanity’s future • All problems trace to one ultimate cause – growing human population

3. Pollution • One major issue is pollution • air pollution - major problem in the world’s cities • Industrial pollution creates gray-air cities • Sulfur oxides main culprit • Ex. NYC and Boston • Automobile pollution creates brown-air cities • Pollutants react with sunlight to form smog • Ex. LA • water pollution • lakes and rivers becoming increasingly polluted with sewage • fertilizers and insecticides washed from land to water • May cause eutrophication

4. Figure 24.7

5. Pollution • Large quantities of toxic chemicals circulate in ecosystem • Many no longer manufactured, but persist in env’t • eg. chlorinated hydrocarbons, such as DDT, banned in US • break down slowly and accumulate in animal fat tissue • bioaccumulation • as pass through the food chain, become increasingly concentrated • biological magnification

6. Biological magnification of DDT

7. DDT in Food Webs • Synthetic pesticide banned in US since the 1970s • Carnivorous birds accumulate DDT • produce brittle egg shells • Crush eggs, so no babies produced • Almost wiped out the brown pelican and bald eagle

8. DDT in Food Webs • DDT in marine mammals • Males and non-reproducing females have high levels • Reproducing females have lower levels • Moms pass it to babies in milk • DDT can cause: • Sterility • Cancer • negative effects on nervous system, liver, kidneys, and immune system

9. Acid Precipitation • Acid rain = pollution-acidified precipitation • sulfur products of industry combine w/water vapor • destroys life • at least 1.4 million acres of forests in Northern Hemisphere adversely affected • Tens of thousands of lakes in NE US and Canada are dying biologically as pH levels fall below 5.0 • Destroys buildings and statues • industrial scrubbers and the Clean Air Act revision of 1990 have begun to address this problem

12. Major coal-burning power and industrial plants >5.3 5.0-5.1 4.7-4.8 4.4-4.5 5.2–5.3 4.9–5.0 4.6–4.7 4.3–4.47 < 4.3 5.1–5.2 4.8–4.9 4.5–4.6 Average acidities of precipitation in the United States in 1998

13. The Ozone Hole • Life only able to colonize land after formation of ozone layer • evolution of photosynthesis  oxygen  ozone • ozone shield protects earth from harmful UV radiation • Natural fluctuations in thickness depending on temp • starting in 1975, ozone shield began to disintegrate, especially above Antarctica • Area of thinner ozone called an ozone hole • Caused by chloroflourocarbons (CFCs) • Used as refrigerants, aerosol propellants, etc • Worldwide drop in ozone now >3% • Increase in lethal melanoma skin cancer of ~20%

14. The ozone hole over Antarctica 2009 1979 1995

15. Global Climate Change • Burning of fossil fuels has released huge amounts of CO2 into atmosphere • trap infrared light (or heat) • creates a greenhouse effect • other greenhouse gases include CFCs, nitrogen oxides, and methanes • Deforestation also contributes • Trees take in CO2 • Trees burned  adds CO2 • Earth’s greenhouse effect is intensifying • Global warming is an increase in global temp associated w/CO2 and other greenhouse gases in atmosphere

16. Solar radiation Radiated heat (reflected radiation) Stratosphere Clouds Earth Figure 24.2

17. The greenhouse effect

18. Dairy cows in San Joaquin Valley, CA, produce more smog-forming gases than cars • according to local air quality regulators • The region's dairy industry currently includes some 2.5 million cattle

19. New Zealand - over 50% of greenhouse gas emissions arise from sheep burps! • methane • 45 million sheep outnumber human population by more than 11 to one

20. Loss of Biodiversity • Extinction is natural – all species go extinct eventually • >99% of all known species now extinct • Current rates of extinction alarmingly high resulting in biodiversity crisis • Three major factors play a role in extinction • habitat loss • single most important cause • species overexploitation • species hunted or harvested by humans at risk of extinction • introduced species • introduction of exotic species results in extinction of native species • no native predators to keep populations in check

21. Factors responsible for animal extinction

23. Overexploitation • Harvesting of a species at unsustainable rates

24. Species Introductions • Introduction of nonindigenous species can decimate a community • Called exotic species • Becomes part of its new community • No natural enemies or controls • Can outcompete native species • ex. San Francisco Bay • ex. Zebra mussels in great lakes • ex. Mongoose in Hawaii • ex. Kudzu in south U.S.

26. Mongoose in Hawaii • Mongoose introduced in 1883 to solve rat problem • Mongoose are diurnal (active during day) • Rats are nocturnal (active at night) • So didn’t work • Now mongoose kill off native birds and transmit diseases

27. Kudzu in Georgia • “the vine that ate the South” • Imported for erosion control • No natural herbivores, pathogens, or competitors • Grows over landscapes and cannot be dug up or burned out • Smothers native plants • May turn out to have some commercial use

28. Endangered Species • Endangered species: A species that is extremely vulnerable to extinction • Extinction = permanent death of an entire species • Close to 70% of endangered species have been negatively affected by exotic competitors • In U.S. alone, 500 species extinct in last 200 yrs • 250 of those in last 25 years

29. What Can We Do?

30. Finding Other Sources of Energy • Decrease reliance on fossil fuels • Reduce air pollution • Reduce CO2 into atmosphere • Alternative energy sources include: • Solar energy • Nuclear energy • Wind energy • Renewable biomass

31. Preserving Nonreplaceable Resources • In US, three types of nonreplaceable resources being reduced at alarming rates • topsoil • over one quarter of topsoil has been lost since 1950 • Takes 100 years to form 1 inch of topsoil • groundwater • groundwater in aquifers is being depleted or polluted • biodiversity • loss of species creates instability in ecosystems and reduces productivity

33. Owens Lake • L.A. started bringing in water from Owens Valley in 1913 • Owens Lake was dry by 1926

34. Owens Lake Today! • 2001 LADWP rediverted water • Now ankle-deep and home to many birds!!

35. Mono Lake • Lake in Sierra Nevadas • L.A. started diverting water in 1941 • Water level was at 6,417 ft • Water level dropped 46 feet and salinity increased dramatically • Affected many birds • In 1989 court ordered halt to water diversions • Mono Lake is currently back to 6,383 ft • The goal is 6,392 ft

36. Mono Lake 1962 1968 1995

37. Curbing Population Growth • All major problems stem from growing human population • world population will hit 7 billion this year • will double in about 58 years • planet cannot support continued growth of this nature • slowing population growth will help sustain the world’s resources • per capita consumption also important

39. Curbing Population Growth • Developed countries have greatest impact • 20% of world population, but use over 50% of resources • We need to lessen our impact • ecological footprint - amount of productive land required to support an individual at the standard of living of a particular population through the course of his or her life • ecological footprint of an individual in the US is 10X greater than that of someone in India

42. Toward a Sustainable Future Consume less Recycle more Support sustainable agriculture Support green roofs Lower worldwide fertility rate Reduce rural world poverty Conserve energy at home Use environmentally preferable products Protect ecosystems that provide ecoservices